Commissioning
8.4 Commissioning the Modules
S7-300, CPU 31xC and CPU 31x: Installation
8-12 Operating Instructions, Edition 08/2004, A5E00105492-05
8.4.4 Formatting the Micro Memory Card (MMC)
You must format the MMC in the following cases:
• The MMC module type is not a user module
• The MMC is not formatted
• The MMC is defective
• The content of the MMC is invalid
The content of the MMC is marked invalid
• The
Load user program
operation was interrupted as a result of Power Off.
• The
Write RAM to ROM
operation was interrupted as a result of Power Off.
• Error when evaluating the module content during CPU memory reset.
• Formatting error, or formatting failed.
If one of these errors has occurred, the CPU prompts you for yet another memory reset,
even after a memory reset operation has been performed. The card's content is retained until
the MMC is formatted, unless the Load user program / Write RAM to ROM operation was
interrupted as a result of Power Off.
The MMC is only formatted if a reason for formatting exists (see above) and not, for
example, when you are prompted for a memory reset after a module replacement. In this
case, a switch to MRES triggers a normal memory reset for which the module content
remains valid.
Use the following steps to format your MMC
If the CPU is requesting a memory reset (STOP LED flashing slowly), you can format the
MMC by setting the selector switch as follows:
1. Toggle the switch to the MRES position and hold it there until the STOP LED lights up
and remains on (after approx. 9 seconds).
2. Within the next three seconds, release the switch and toggle it once again to MRES
position. The STOP LED flashes to indicate that formatting is in progress.
Note
Always perform this sequence of operation within the specified time. Otherwise, the MMC
will not be not formatted, but rather returns to memory reset status.
See also
CPU memory reset by means of mode selector switch (Page 8-9)
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